Mepolizumab has received a positive recommendation for subsidy on the Pharmaceutical Benefits Scheme (PBS). Mepolizumab is indicated as add-on therapy for severe refractory eosinophilic asthma in patients aged twelve years and over. This monoclonal antibody is directed against interleukin-5; a major cytokine responsible for the maturation, activation, and survival of eosinophils.

Clinical trials demonstrate an 86% reduction in blood eosinophil counts after twelve weeks of monthly subcutaneous injections. After 32 weeks, this translated to a 69% reduction in exacerbations requiring hospitalisation and a 98ml increase in pre-bronchodilator forced expiratory volume in one second (FEV1). Another study demonstrated a 50% median reduction in oral glucocorticoid dose in the mepolizumab-treated group compared to 0% in the placebo group.

As part of their economic analyses, the Pharmaceutical Benefits Advisory Committee (PBAC) proposes that 100mg of mepolizumab every four weeks is equi-effective to omalizumab 398mg every four weeks. Indirect comparisons suggest that mepolizumab is non-inferior to omalizumab regarding safety and efficacy.

Hypersensitivity reactions including urticaria, angioedema, and bronchospasm have occurred during mepolizumab therapy. These reactions usually occur within hours of administration. However, some reactions may be delayed. Due to the proposed role eosinophils play in responding to helminth infections, pre-existing infections should be treated before initiating mepolizumab. A small number of serious herpes zoster infections occurred during clinical trials. Consideration should be given to the need for herpes zoster vaccination before therapy begins.


  1. Bel EH, Wenzel SE, Thompson PJ, Prazma CM, Keene ON, Yancy SW, et al. Oral glucocorticoid-sparing effect of mepolizumab in eosinophilic asthma. New Eng J Med. 2014; 371(13): 1189-97.
  2. Nucala® (mepolizumab) Australian approved product information. Abbotsford: GlaxoSmithKline Australia. Approved February 2016.
  3. Ortega HG, Liu MC, Pavord ID, Brusselle GG, Fitzgerald JM, Chetta A, et al. Mepolizumab treatment in patients with severe eosinophilic asthma. N Engl J Med. 2014; 371: 1198-207.
  4. Pharmaceutical Benefits Advisory Committee. Mepolizumab Public Summary Document – July 2016 PBAC Meeting. Canberra: Australian Government Department of Health, 2016.

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